The invention relates to the field of optical switching relays, and in particular to a pressure actuated optical relay that latches by means of a liquid metal.
Communications systems using optical signals require the use of optical switches and routers. An early approach to optical switching was to convert the optical signal to an electrical signal, use an electrical switch or router and then convert back to an optical signal. More recently, optical relays have been used in which an electrical control signal is used to control the switching or routing of an optical signal. Optical relays typically switch optical signals by using movable solid mirrors or by using the creation of bubbles in liquid. The moveable mirrors may use electrostatic latching mechanisms, whereas bubble switches do not latch. Piezoelectric latching relays either use residual charges in the piezoelectric material to latch, or actuate switch contacts containing a latching mechanism.
This invention relates to a pressure actuated optical relay that uses a liquid metal, such as mercury, as a switching mechanism and as a latching mechanism. The relay contains a transparent mirror housing, located at the intersection of two optical paths. A solid slug is moved within a channel passing through the transparent mirror housing by the action of pressure in an actuation fluid. A surface of the solid slug is wetted by a liquid metal to form a reflective surface. The solid slug is moved in or out of the transparent mirror housing to select between the optical paths. When the solid slug is within the optical path, an incoming optical signal is reflected from the reflective surface of the liquid metal, otherwise the optical signal passes through the transparent housing. Wettable metal surfaces within the channel provide a latching mechanism.